1. Field of the Invention
The present invention relates to an LED illumination device; and more particularly, to an LED illumination device having a good radiation effect and an excellent visual effect by being provided with a plurality of radiating fins and a case covering the radiating fins.
2. Description of the Related Art
An LED (Light Emission Diode) element represents an element emitting predetermined light through the recombination of a minority of carriers (electrons and holes) after generating the carriers injected by using a p-n junction structure of a semiconductor. The LED element includes a red LED element using GaAsP, a green LED element using GaP, and a blue LED element using an InGaN/AlGaN double hetero structure.
The LED element has low power consumption and a long lifetime, and a vibration resistance characteristic. The LED element can be installed in a narrow space. The LED element has been used as a display element and a back light. Recently, the LED element has been actively researched and developed so as to be applied for a general illumination apparatus.
However, only 20% of energy inputted into an LED illumination lamp is converted into the light and the rest 80% of the inputted energy is converted into heat in a junction portion according to a light generation characteristic of an LED lamp, thereby increasing an internal temperature. The increment of the internal temperature substantially degrades a performance of the LED illumination lamp.
That is, the efficiency of the LED illumination lamp is curtailed by the emission of the heat at the time of using the LED illumination lamp for a predetermined time and a heating value of the LED illumination lamp increases at the time of using the illumination lamp for a long time, thereby curtailing a lifetime of the LED illumination lamp.
Accordingly, in order to preventing the curtailment of the lifetime of the LED illumination lamp due to the long-term usage and the excessive heat emission of the LED illumination lamp, the heat generated in the inside of the LED lamp needs to be discharged to the outside.
Particularly, in case of a high-output LED lamp, since LED chips are densely integrated in the narrow space, a rapidly increasing temperature in the junction portion needs to be effectively radiated.
In prior art, a method of cooling the heat of the LED lamp by convection by means of a radiator having a radiating fin structure was used so as to discharge the heat of the LED lamp.
FIG. 1 shows an LED illumination device provided with a radiator having a conventional radiating fin structure.
As shown in FIG. 1, a conventional LED illumination device 10 includes a printed circuit board 12 mounted with a plurality of LED chips 11 and a radiator 15 provided on the other surface of the printed circuit board 12 on which the LED chips 11 are not mounted.
The radiator 15 includes a radiating plate 13 mounted with the printed circuit board 12 and radiating fins 18 provided below the radiating plate 13. The radiating fins 18 radially protrude on an outer circumference surface of a cylindrical support 16.
The cylindrical support 16 is mechanically joined with the radiating plate 13.
In the above-configured conventional LED illumination device 10, when a signal is applied to the printed circuit board 12, light and heat is generated from the LED chips 11 at once. The heat generated from the LED chips 11 is transmitted to the radiating plate 13 and the light transmitted to the radiating plate 13 is transmitted to the radiating fins 18 through the cylindrical support 16 provided below the radiating plate 13. The light transmitted to the radiating fins 18 is radiated by natural convection.
As described above, the conventional LED illumination device 10 discharges the heat through the radiating fins 18. At this time, since the larger the surface areas of the radiating fins 18 is, the better a radiation effect is, the radiating fins 18 protrude radially to run outward from the cylindrical support 16.
As described above, there is an advantage in that the radiation effect can be raised at the time of radially form the radiating fins 18, but since the radiating fins 18 are exposed to the outside, the LED radiation lamp has a dirty exterior and has a low visual effect.